How to understand the process of auto-populating the Number (Title)?

Hello everyone!

Have possibly a dumb question.

I have a section (Classic UI) where the number (title) is auto-populating from 3 different lookups. So basically, the title consists of 1st lookup +2nd lookup +3rd lookup.

I need to understand the logic behind this and how to customize it (to change these fields if needed). I do not see any business rule or business process involved in it. Is there any other way it could be done, except coding? How to find the process behind it, or else?

Thanks in advance.